Morphological variability and ecological characterization of the Chagas disease vector Triatoma dimidiata (Hemiptera: Reduviidae) in El Salvador.

There are 8 million people with Chagas disease worldwide and in El Salvador approximately 39% of the population is at risk of contracting the disease. One of the principal challenges in mitigating Chagas is evaluating the role of the vector ecology of triatomine species in the transmission of the Trypanosoma cruzi parasite in anthropogenically modified habitats, where new patterns of transmission frequently arise. Field studies of triatomine vector ecology in El Salvador have largely focused on describing parameters that contribute to infestation patterns, which may themselves be rooted in the morphological variability that exists in triatomine populations. The objective of this study was to evaluate the morphology of the vector species Triatoma dimidiata with respect to the characteristics of the ecological landscape the vector inhabits throughout El Salvador. We used image analyses to evaluate T. dimidiata morphological variability and then used Geographic Information Systems to intersect the morphological point-data with map layers containing different environmental characteristics. Our study found that the variation in the size, shape, and coloration of T. dimidiata varied in relation to elevation, Holdridge life zone, soil type and land use. We further characterize the local morphological adaptations of T. dimidiata with respect to the local ecological, biological, and geographical conditions in El Salvador. We suggest that future studies consider a molecular exploration of local T. dimidiata species complex in El Salvador, especially since morphological studies of triatomine species complex have found that variability correlate with the genetic variability of the population.